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October Newsletter

Air Quality

Scientists from USDA's Agricultural Research Service (ARS) are taking a sideways look at odors, literally.

As anyone that has evaluated potential sites for swine facilities knows, many factors--such as wind speed, direction, topography, vegetation, and more--influence the potential impacts on downwind neighbors. In an effort to understand how air currents interact with the building site--and therefore pick up odors, dust, and other emissions--Tom Sauer and Jerry Hatfield, with the National Soil Tilth Laboratory in Ames, Iowa, built a model swine farm in a wind tunnel.

Research Activities

Air flow velocities and turbulence intensities were measured with a sensor that measured how quickly the winds carried heat away at 83 points behind the building models. They also took pictures of smoke patterns, generated by dry ice, to capture airflow patterns around the model structures and measured evaporation rates from the model storage tanks and lagoons. They reconfigured the model farm in different ways and repeated their measurements.

What Did They Learn?

Buildings situated perpendicular to airflow disrupted downwind airflow to a greater extent than buildings parallel to airflow. “These studies show how much the placement of animal housing units and manure-storage facilities can work in combination with prevailing winds and site conditions to affect the distance that potential agricultural air emissions can travel,” says Sauer. “They strongly indicate that we should be able to reduce the downwind air-quality impacts from animal production by modifying the layout of a production facility.”

Using model farm buildings, silos, and trees (wire mesh coils serve as trees), agronomist Guillermo Hernandez (left) and soil scientist Tom Sauer evaluate the effect of model arrangements on airflow. Hernandez makes an adjustment to one of the highly sensitive probes as Sauer monitors the real-time data signal. Photo courtesy of the USDA Ag Research Service.

Additional Information

• "Tunnel Vision" Tracks Emission Dispersal was published in the September 2008 issue of Agricultural Research magazine.
• This research is part of Air Quality, an ARS national program (#203).
• Thomas J. Sauer and Jerry Hatfield are with the USDA-ARS National Soil Tilth Laboratory, 2110 University Blvd., Ames, IA 50011-3120; phone (515) 294-3416 [Sauer], (515) 294-5723 [Hatfield].

October, 2008 Newsletter Articles

• EPA Releases "Report on the Environment 2008"
• Orienting Buildings Perpendicular to Prevailing Winds May Reduce Odors
• Poultry Waste Management Symposium To Be Held October 21-23
• US Geological Survey National and Regional Trends in Ground-Water Quality

This summary was adapated from materials provided by the USDA ARS. It has not been peer reviewed and represents the newsletter editor's summary of the research.